oracleidgenerator.java

根据Scott W. Ambler在1998年写的关于ORM Persistence Layer的详细设计论文的设计思路,Artem Rudoy 开发了一个开源的ORM实现 -- PL(Persist

package pl.test;

import java.sql.Connection;

/**
 * ID generator for the Oracle database.
 *
 * @author: Artem Rudoy
 */
public class OracleIdGenerator extends AbstractHighLowIdGenerator
{
/**
 * OracleIdGenerator constructor.
 */
public OracleIdGenerator()
{
	super();
}
/**
 * Return new high value.
 *
 * @return new high value
 */
protected long getNextHighValue(pl.map.ClassMap classMap) throws pl.PlException
{
	Connection conn = null;
	long highValue = 1;
	try
	{
		conn = classMap.getRelationalDatabase().getConnection();
		java.sql.PreparedStatement pst = conn.prepareStatement("SELECT id_generator.nextval FROM dual");
		java.sql.ResultSet rs = pst.executeQuery();
		if(rs.next())
		{
			highValue = rs.getLong(1);
		}
		rs.close();
		pst.close();
		conn.commit();
		classMap.getRelationalDatabase().freeConnection(conn);
	}
	catch (Throwable e)
	{
		throw new pl.PlException(e);
	}
	highValue <<= 16;
	highValue &= 0xffffffffffff0000L;
	return highValue;
}
}